1. Field of the Invention
The present invention relates to a method of determining at least one traffic route in an MPLS (Multi-Protocol Label Switching) network.
2. Description of the Related Art
An MPLS ensures quality of service (QoS) for a traffic transported through an IP (Internet Protocol) network and efficient use of network resources. Therefore, it is spotlighted in traffic engineering field.
The MPLS traffic engineering determines an LSP (Label Switched Path) in various ways to appropriately accept a variety of QoS demands for users' IP packets. The LSP is a point-to-point (PTP) path connecting from an ingress to an egress edge router.
The IETF (Internet Engineering Task Force) committee is under discussion about reroute, protection switching, and fast reroute in determining an LSP to prepare against unexpected network fault. The methods of protection switching and fast reroute reserve a backup path for a primary LSP to prepare against network fault. However, when a backup path is reserved, some bandwidth of the backup path is reserved and is not able to be used for other traffic.
Another method has been proposed to resolve such a drawback. In this method, a reserved backup path is used for other traffic demanding low QoS in case of normally-operative network and for a traffic of primary LSP in case of faulty network.
Despite such an improved method, new methods are still demanded to prepare for network fault while reducing a bandwidth allocated for a backup path as possible as it can.
In addition, conventional methods consider only current traffic being routed through network as link or node cost in LSP determination. In other words, they do not consider traffic to be routed at all, which restricts the most optimal path determination from an overall network point of view. Therefore, such conventional methods reveal low efficiency of traffic engineering.
In the meantime, due to rapid growth of an IP base network, various multimedia services such as VoIP, VOD, AOD, on-line movie, and video conference are being demanded. Many of those multi-media services require a point-to-multipoint (PTM) tree. If a PTM multimedia service is provided through PTP LSPs, use efficiency of network resources becomes worse and/or management of QoS becomes not easy. This is because multicast traffic is routed through a unicast way.
In the Internet proposal room of the IETF committee, many ways to distribute MPLS label are being listed up. Those many ways use PIM-SM or PIM-DM which is conventional multicast IP protocol. Besides the proposed many ways, MPLS multicasting way is being standardized in the IETF.
However, since tree determining methods of existing multicast protocols proposed until now are all receiver-based, it is not easy to reflect intentions of a service provider or users appropriately. Furthermore, a multicast traffic transporting method using an existing PTP path determining way can not use network resources efficiently, which results in deterioration of service quality.
In addition, all existing tree determining methods consider only current network state, namely they do not consider traffic to be routed at all, which causes a problem that traffic load is not distributed uniformly over an overall network.